This two-day conference, ?Per- and Polyfluoroalkyl Substances: Second National Conference,? will be held at Northeastern University in Boston in June 2019, under the auspices of the Social Science Environmental Health Research Institute (SSEHRI), and coordinated by a planning committee of research scientists, community leaders, and government scientists. The conference will examine the social, scientific, political, and environmental health issues raised by the continual discoveries of water contamination and elevated exposures to per- and polyfluoroalkyl substances (PFASs). The period since the first conference in June 2017 has been marked by many developments, including growing numbers of identified contaminated sites, establishment of new lower PFAS drinking water guidelines in many states and the setting of regulatory levels in two states, the formation of a national coalition of affected communities, involvement of Senators and Representatives, launching of a nationwide study of military sites by the Department of Defense, new scientific findings, a May 2018 Summit, and near-daily news reporting in local and national media. Of special importance is that PFAS research, education, and engagement is part of several Superfund Research Program (SRP) Centers, including the new University of Rhode Island SRP entirely focused on PFAS (STEEP). Based on the 180 attendees at the 2017 conference and growing national interest in PFASs, we expect at least 200 conference attendees, including scientists; government agency professionals; members of community-based, regional, and national environmental organizations; retail and industry representatives; journalists; lawyers; water utility professionals; and environmental consultants. We will promote new interdisciplinary and community-engaged research, and lead to better understanding of PFASs with regard to science, regulation, remediation, prevention, community engagement, and development of alternatives to these widely used chemicals. Throughout, we will emphasize the overarching goal of assisting in cleanups and reducing future contamination. This conference will achieve three specific aims: 1: Conduct a conference on the social, scientific, political, and environmental health issues raised by the growing discoveries of water contamination and human exposure associated with PFASs, 2: Provide a setting to enhance existing, and create new, collaborations, 3: Disseminate findings and expand ongoing website resources for information exchange and data archiving. In terms of relevance to NIEHS' Strategic Plan, this conference aligns with Theme I: Advancing Environmental Health Sciences, Theme II: Promoting Translation, and Theme III: Enhancing EHS through Stewardship and Support. The Organizing Committee will be composed of PI Phil Brown (Northeastern), Laurel Schaider (Silent Spring Institute), Andrea Amico (Testing for Pease), Sylvia Broude (Toxics Action Center), Shaina Kasper (Toxics Action Center), Alissa Cordner (Whitman College), Courtney Carignan (Michigan State), Andrew Lindstrom (EPA), and Lauren Richter (Northeastern and Silent Spring Institute).